高温后钢筋混凝土框架抗震性能试验研究

为研究高温后混凝土框架的抗震性能,设计了2个强梁弱柱框架和2个强柱弱梁框架,预先对其中2个框架进行明火升温试验,然后对所有试件进行低周往复加载试验.考察了各榀框架的破坏模式、荷载-位移关系、承载力、变形能力、刚度和耗能能力与高温和梁柱尺寸等因素的关系.试验结果表明:受火后混凝土框架的承载力和耗能能力有所降低,强梁弱柱型框架的承载力下降更为明显,且屈服位移增大,极限位移减小;受火后混凝土框架的塑性铰出现顺序改变为柱底—梁端—柱顶,柱端更容易出现塑性铰.常温下强柱弱梁型(破坏形态为梁端先出现塑性铰)框架在火灾后可能转化为"强梁弱柱"型破坏.

Quasi-static Test of Reinforced Concrete Frames After High Temperature

To investigate the seismic performance of reinforced concrete (RC) frames after high temperature, two strong-beam-weak-column frames and two strong-column-weak-beam frames were designed. Two of the frames were subjected to fire test, then low-frequency cyclic loading tests were conducted for all the specimens. The variation of failure modes, bearing capacities, load-displacement relationship, deformability, stiffness, and energy dissipation as the endured greatest temperature and the beam-column size relation was analyzed. The test results show that the bearing capacities and energy dissipation capacities of the RC frames were reduced after fire, and the reduction of those of the strong-beam-weak-column frames was more serious. The yield displacement increased and the ultimate displacement decreased. After fire, the plastic hinge first occurred at the bottom of the column, then the beam end, and then the top of the column, which indicates the plastic hinge tended to appear at the column ends. The RC frames designed according to strong-column-weak-beam criterion (in which plastic hinges first appear at the beam-ends) may fail in the form of strong-beam-weak-column after fire.